00:01
MARINA: Hello, my name is
Marina and I am
00:04
currently a student
at BYU-Idaho.
00:06
And today I will be
talking about functions.
00:09
A function is a group
of statements or
00:12
computer commands that
00:13
together perform a task.
00:15
There are different
types of functions,
00:17
including built-in
functions.
00:19
We can also build our own,
00:21
but we will focus on
00:22
that in the
following weeks.
00:24
So let's start with a
simple input function.
00:28
For that, we will
have to create
00:30
a variable called age.
00:36
We will see input,
put parentheses, and
00:39
inside of quotation marks
we will ask our question.
00:47
Something to keep in mind
00:49
is when we use an
input function,
00:52
the response from the user
00:54
is automatically string.
00:56
If we want to work
with numbers,
00:58
we would have
to convert it,
01:00
use it int or float,
01:02
which are both built-in
Python functions.
01:06
For example,
if we use int,
01:09
we wrap it around
our input function.
01:12
And it would give us
01:15
a whole positive
number, an integer.
01:18
If we want a float
instead of int,
01:22
we just type in float.
01:24
And that will result
with a decimal,
01:28
but is usually
used for decimals.
01:31
So, for example, if we work
01:33
with prices or such,
01:35
this would be a helpful
tool to use.
01:38
So we can just
leave it at float.
01:42
Notice in line 3,
so far we have called
01:47
two built-in functions,
float and input.
01:51
And now we're going to
01:53
call another
function, print.
01:58
Inside the parentheses,
02:01
we will say H, because
that's what we
02:04
want to be displayed
02:05
after the user
answers the question.
02:09
Let's run the code
and see how it works.
02:15
As you can see, a question
02:18
is asked, how old are you?
02:20
any number, for
example, 20.
02:30
is shown up under
the question,
02:34
and we see that there's
02:36
a dot with a zero after 20.
02:38
And that is
because we left
02:40
it at float function,
02:42
which means it converted
to a decimal.
02:45
To call the function,
02:46
we should keep in
mind three things.
02:49
The name of the function,
02:52
it was print function,
float function,
02:56
the parameters that
the function takes,
02:59
and what the function does.
03:01
To call a function
means to write
03:03
a code that causes
the computer to
03:06
execute the code that
03:07
is inside that function.
03:09
It is important to know
03:11
the difference between
03:13
a parameter and
an argument.
03:15
A parameter is a
piece of data that
03:19
order to complete
its task.
03:21
An argument is
the value that
03:23
is passed or a parameter
into a function.
03:26
For example, in line five,
age is an argument.
03:33
Now, let's talk about
03:36
optional versus
name arguments.
03:43
When we write a function,
then call it,
03:46
we would write
the arguments
03:48
inside the parentheses.
03:49
Some arguments
are required,
03:51
and others are optional.
03:54
For example, if we want to
03:55
find out things
about a student,
03:58
will get asked for
their first name,
04:00
last name, and major.
04:01
So, let's start with that.
04:03
Again, we will
create a variable.
04:07
Last name, we will
equal it to input,
04:13
the question in
the quotations.
04:22
Notice that I left it at
04:26
just in but without
using int or float.
04:29
And that's because we are
04:31
expecting to get a
string from the user.
04:34
And int and float is
used for numbers.
04:38
So here we create it.
04:40
Last name, and then we're
creating the first name.
05:05
As you can see, lines
three through five,
05:10
we called the input
function three times.
05:18
An option argument can include
05:22
something like the
separate argument.
05:30
you it in the
print function.
05:33
So, if we want to
display the first name,
05:38
last name, and the major of
a student in the print function,
05:41
we will specify those
variable names.
05:47
First name, last name, major.
05:51
Now, after the comma,
05:54
we would rate our
separate argument.
06:01
I'm going to put
space and then we can
06:04
put all sorts
of characters.
06:10
it could be a slash,
anything like that.
06:14
And this time I'm just
going to use a bar.
06:17
And that leads us into
the name arguments,
06:21
which is this highlighted
part in line seven,
06:27
which shows that
we specifically
06:31
gave a name to
the argument, we
06:33
specified what we
want it to be.
06:37
So let's run
the code again.
06:45
it's asking us for
the last name.
06:50
What is your first name?
06:53
And major can be CIT.
06:59
As you can see, without
us doing it manually,
07:06
after each input,
there was a bar.
07:10
So, each variable
was separated.
07:15
Module is a collection
of related functions.
07:20
Python has a
standard library
07:22
with different modules.
07:24
For example, math module.
07:26
Before we start calling
07:28
any functions, in order
to use a math module,
07:31
we will have to import that.
07:36
we write the name
import, then math.
07:43
In this example, we'll ask
07:45
the user for an
area of a square.
07:51
we have a new variable
called area...equals,
07:56
and in this time we'll
use float again,
08:01
because sometimes an
area can be a decimal.
08:06
Inside, we will have
our input function.
08:12
Again, in quotations,
08:14
we will ask the question,
08:16
"What is the area
of the square?"
08:23
And we will be
specific and
08:25
say in square inches.
08:34
In line six,
we're going to
08:37
calculate the side
of that square.
08:41
We will begin by naming
a variable side.
08:45
And we will
equal it to map.
08:50
Well, we have imported in
08:53
line three, and we put
dot, square root.
09:00
And we're going
to square root
09:03
whatever number
the user is
09:04
going to give us--that area.
09:09
Now, let's have the
print function.
09:20
And we will say, "The size
of a side of the square is..."
09:35
And we will use the side
variable because
09:39
that's the number
that we want to
09:44
And we will say that
it will be in inches.
09:53
we have two different
functions called float and input.
10:00
we're using the
Math Module to
10:05
square root the
input from the user.
10:12
we're going to display
that calculation.
10:16
So far, we have
stored a lot
10:19
of different variables
in our code,
10:23
but we are not required
10:25
to do that every time.
10:28
For example, we can use
10:29
the same examples
we have here.
10:33
And instead of creating
the side variable,
10:37
we can copy this part,
10:47
and insert it
in line eight,
10:50
and we can remove
remainder of line six.
10:56
Now, let's run the code.
11:01
Here on the bottom, it says,
11:03
"What is the area of the
square in square inches?"
11:07
We can say
something like 64.
11:11
As a result, we get the
size of the side of
11:14
the square is
eight inches.
11:17
So everything
works correctly.
11:19
Notice again that
point zero after the eight,
11:26
the float function
in line five.